Combination drawing instrument



Nov. 1, 1932. J. c. soMMER COMBINATION DRAWING INSTRUMENT John GSOmmer Filed Nov. 1, 1930 Patented Nov. 1, 1932 PATENT OFFICE J'OHNO. SOMMER, OF ST. LOUIS, MISSOURI COMBINATION DRAWING IN STBUMENT Application filed November 1,1930. Serial No. 492,698.

This invention relates to a drawing element. The essential objects'of the invention are to so construct and arrange the instrument to provide for drawing curvatures of various sizes and nature in various relative positions and proper conjunction with each other; lo-

cating certain points, centers, foci and lines of axes; to obtain measurements and dimensions. of axes and distances, and to obtain these ends in a strong, durable, thoroughly eflicie'nt, readily adjustable and comparatively inexpensive structure;

To the above ends essentially my invention consists in such parts and such combination of parts as fall within the scope of the invention as claimed.

In the accompanying drawing Figure 1 is a fragmentary view inelevation of a drafting instrument in accordance with this invention.- 4

Figure 2 is an elevation'ofa reversible 7 point piece.

Figure 3 is a like view of a scribing member.

The'instrument includes a compass element 1 having a pair of oppositely extending arms 2 pivotally connected together at one end and capable of being shifted towards and from each other. Pivotally connected to the other end of each arm 2, as at 3 is a socket forming member 4 carrying a pair of set screws 5. Extending transversely through the members 4 and projecting at rightangles thereto are slidably adjustable supporting of the set screws 5 carried by each member 4. Supported by one of the arms 2 is a winding reel 7 for a guide 15 in the form of a strap of flexible material provided with indicia 16.

The instrument also includes an automatically operable coadjusting center-indicating element consisting of two pair of links '8.

The links of each pair havetheir inner'ends pivotally connected in a socket piece 9. The socket pieces 9 are connected together by an expansible and constractile center indicating member 13. I

Extending into each socket forming mem ber land secured'thereto by the other set screw 5 is a point piece 12 having a stem 10 a holder not shown.

bars 6 retained in adjusted position by one terminating in a shank 11 which extends into member 4:. The shank 1O abuts the non--- pivoted end of member 4 and is provided Wltll a socket into which extends the outer end of a link of each pair of links. The center indicating element is in the form of'a toggle and the outer ends of the links 8 are permanently maintained in the stems 10 on the adjusting of the divider or compass element 1 due to the action of member 13.

During the adjustment of the element 1 the member 13 maintains center position, thus indicating the minor axis-line of an ellipse, while the point pieces 12 are on the foci in the major axis-line.

The point pieces 12 below the shanks 10 are slotted for the passage of the guide 15, and a portion of the length of the latter is detachably anchored to the by the clamping screws 14.

Ascribing member is indicated at 17 carrying a marker 18. The element 17 is formed with a slot for the passage of guide 15 and also'include's a shank 19 for connection to When member 17 .is attached to guide 15 and drawn with'an out-, ward tension with respect to guide 15 it'will describe an elliptical curve A indicated by the dot and dash line showing Figure 1. The distance from either foci point to any point on the elliptical curve can be determined by reference to the graduations '16, while the length of the major axis can be determined by 7 reference to the graduations 16 reading from one point piece 12 to the other. That portion of the guide8 between the point pieces 12, when used in connection with member 17 to provide the elliptical curve is in the form of a sling.

Detachably connected to one of the arms 6' is a circle drawing element consisting of a shank 21 having an apertured point and carrying a protractor portion 20 provided with indicia for indicating the degrees of arc of the circular curves B indicated by the dot and dash line showing Figure 1. The degree being indicated by the indicia included between the initial ,and finalpositions ofthe guide 22 which passes through the portion 20 and point of the shank and is attached to the point pieces I 12 v scribing member 23. The stem 21 extends up through the arm 6 and is detachably connected to the latter. The guide 22 is in the form of a cord.

Detachably connected to the other arm 6 is a spiral drawing element consisting of a stem 24 provided with a shank 25 and an apertured point. Carried by the stem 2 1 is an annulus 26 provided with indicia on its periphery for indicating the extent of the spiral curve C by the indicia included between the initial and final contact points of the guide 27 which extends through the annulus 20 and is attached to an eye 29 formed on a scribing member 28. The guide 27is in the form of a cord. The curve C is indicated by the dot and dash line showing Figure 1.

Supports 30 are detachably connected to the stem 21 and shank 25 and each support carries a combined Winding and clamping fixture 31, only one shown. One fixture being for adjusting the guide 22 and the other for the guide 27.

The form of point piece shown in Figure 3 consists of a rotatable stem 32 terminating at one end in an apertured point portion 33 and at its other end in a slotted point portion 34, whereby provision is made for the use of the point piece in connection with a guide in the form of a cord or strap. The stem 32 is journaled in a sleeve 35 arranged between the point portions.

In Figure 3 a form of scribing element is shown, consisting of a shank 36 for attachment to a holder, a bracing portion 37, a pen point 38 and an eye 39 for connection to a guide. The bracing portion has a knob 40 for riding upon the drawing surface.

It is obvious that the guide 22 can be con-V nected to the points of the circle and spiral drawing elements, as shown by dotted lines and the elliptical curve D be drawn exterior to curve A. As shown the circular curve B and the spiral C are joined to the curve A.

The arms 6 are formed of sections enabling them to be bent whereby the point pieces may be variously positioned and by connecting the sling of a guide to different point pieces, curves of different sizes, nature and position and conjunction can be drawn in fitting accordance.

It is understood that the guides may be of flexible wire, string, or tapeline or the like; also that the numerous points may be frictioned or lockable, or of screw-tightened nature; also that certain parts may vary in proportion for drawing the desired spaced spirals and curves; also that the means of connection, instead of being shanks and sockets, may be of other nature, and even adapted to joint with accessorial devices not shown; also that the bendable extending arms 6, may be of different design for changeably and adjustably atfixing the elements; and that various changes and modifications can be made within the scope of my invention as claimed without loss of advantages and benefits.

The specific winding and clamping fixture 31, is described and claimed in my co-pending application 492,699 filed November 1, 1930.

What I claim is 1. A drawing instrument comprising an adjustable supporting body of divider-like form, a pair of spaced, opposed socket forming members pivotally connected to said body, a scribing instrument guide for forming elliptical curves and provided with graduations, a point piece attached to each member, a winding reel carried by said body for said guide, means for detachably anchoring a portion of the length of said guide to said point pieces, and an automatically operable combined expansible and contractile center indicating element having opposed ends permanently seated in said point pieces above the anchoring points for said length of the guide.

2. A drawing instrument comprising an adjustable supporting body of divider-like form, a pair of spaced, opposed socket forming members pivotally connected to said body, a scribing instrument guide for forming elliptical curves and provided with graduations, a point piece attached to each member, a winding reel carried by said body for said guide, means for detachably anchoring a portion of the length of said guide to said point pieces, and an automatically operable combined expansible and contractile center indicating element having opposed ends permanently seated in said point pieces above the anchoring points for said length of the guide, and said point pieces having openings for the passage of said guide.

3. A drawing instrument comprising an adjustable supporting body of divider-like form, a pair of spaced, opposed socket formin g members pivotally connected to said body, a scribing instrument guide for forming elliptical curves and provided with graduations, a point piece attached to each member, a winding reel carried by said body for said guide, means for detachably anchoring a portion of the length of said guide to said point pieces, an automatically operable combined expansible and contractile center indicating element having opposed ends permanently seated in said point pieces above the anchoring points for said length of the guide, and a pair of laterally extending supporting bars connected to said members and each adapted to have connected therewith curve scribing means.

4. A drawing instrument comprising an adjustable supporting body of divider-like form, a pair of spaced, opposed socket forming members pivotally connected to said body, a scribing instrument guide for forming elliptical curves and provided with graduations, a point piece attached to each member, a

Winding reel carried by said body for said guide, means for detachably anchoring a portion of the length of said guide to said point pieces, an automatically operable combined expansible and contractile center indicating element having opposed ends permanently seated in said point pieces above the anchoring points for said length of the guide, a pair of laterally extending supporting bars connected to said members, means for forming curves of circular form carried by one of said bars, and means for forming curves of spiral form carried by the other of said bars.

5. A' drawing instrument comprising an adjustable supporting structure including a pair of arms pivotally connected together at one end and a pair of opposed socket forming members, each pivotally connected at its inner end to the other end of an arm, a point piece detachably connected to each member and projecting from the outer end of the latter, a scribing instrument guide for forming elliptical curves, a Winding reel carried by one of said arms for said guide, each of said point pieces having an aperture for the passage of said guide, means carried by said point pieces for detachably anchoring said guide at spaced points of the latter to said point pieces, and an automatically operable and self adjusting center indicating element having opposed ends thereof permanently seating in said point pieces.

6. A drawing instrument comprlsmg an adjustable supporting structure including a pair of arms pivotally connected together at one end and a pair of opposed socket forming members, each pivotally connected at its inner end to the other end of an arm, a point piece detachably connected to each member and projecting from the outer end of the latter, a scribing instrument guide for forming elliptical curves, a Winding reel carried by one of said arms for said guide, each of said point pieces having an aperture for the passage of said guide, means carried by said point pieces for detachably anchoring said guide at spaced points of the latter to said point pieces, an automatically operable and self adjusting center indicating element hav- 7 ng opposed ends thereof permanently seating in said point pieces, and means supported from said members for forming curves exteriorly of the curve formed by said guide.

7. In a drawing element, a point piece element including a stem and a point portion at each end of the stem, each of said point portions formed With an opening, one of the openings being in the form of a slot.

JOHN C. SOMMER. 

